algorithm.h

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#pragma once
 
#include "di/meta/constexpr.h"
#include "di/meta/core.h"
#include "di/meta/function.h"
#include "di/meta/list.h"
#include "di/types/integers.h"
#include "di/vocab/tuple/tuple_forward_declaration.h"
 
namespace di::meta {
namespace detail {
    template<typename Pred, typename Type>
    struct AllHelper {};
 
    template<typename Pred, typename... Types>
    struct AllHelper<Pred, List<Types...>> : Constexpr<(meta::Invoke<Pred, Types> {} && ...)> {};
}
 
template<concepts::TypeList List, concepts::MetaInvocable Pred>
constexpr inline bool All = detail::AllHelper<Pred, List>::value;
 
namespace detail {
    template<typename R, typename List>
    struct AsLanguageFunction;
 
    template<typename R, typename... Types>
    struct AsLanguageFunction<R, List<Types...>> : TypeConstant<R(Types...)> {};
}
 
template<typename R, concepts::TypeList T>
using AsLanguageFunction = Type<detail::AsLanguageFunction<R, T>>;
 
namespace detail {
    template<typename T>
    struct AsListHelper {};
 
    template<auto... values>
    struct AsListHelper<ListV<values...>> : TypeConstant<List<Constexpr<values>...>> {};
 
    template<template<typename...> typename Template, typename... Types>
    struct AsListHelper<Template<Types...>> : TypeConstant<List<Types...>> {};
 
    template<typename R, typename... Args>
    struct AsListHelper<R(Args...)> : TypeConstant<List<Args...>> {};
}
 
template<typename T>
using AsList = Type<detail::AsListHelper<T>>;
 
namespace detail {
    template<template<typename...> typename Template, typename List>
    struct AsTemplateHelper {};
 
    template<template<typename...> typename Template, typename... Types>
    requires(concepts::ValidInstantiation<Template, Types...>)
    struct AsTemplateHelper<Template, List<Types...>> : TypeConstant<Template<Types...>> {};
}
 
template<template<typename...> typename Template, concepts::TypeList T>
using AsTemplate = Type<detail::AsTemplateHelper<Template, T>>;
 
template<concepts::TypeList T>
using AsTuple = AsTemplate<vocab::Tuple, T>;
 
namespace detail {
    template<typename...>
    struct ConcatHelper {};
 
    template<typename... Ts, typename... Us, typename... Rest>
    struct ConcatHelper<List<Ts...>, List<Us...>, Rest...> : ConcatHelper<List<Ts..., Us...>, Rest...> {};
 
    template<typename T>
    struct ConcatHelper<T> : TypeConstant<T> {};
 
    template<>
    struct ConcatHelper<> : TypeConstant<List<>> {};
}
 
template<concepts::TypeList... Lists>
using Concat = Type<detail::ConcatHelper<Lists...>>;
 
template<concepts::TypeList L, typename T>
using PushFront = Concat<List<T>, L>;
 
template<concepts::TypeList L, typename T>
using PushBack = Concat<L, List<T>>;
 
template<concepts::TypeList List>
using Join = Apply<Quote<Concat>, List>;
 
namespace detail {
    template<typename T>
    struct PopFrontHelper : TypeConstant<List<>> {};
 
    template<typename T, typename... Rest>
    struct PopFrontHelper<List<T, Rest...>> : TypeConstant<List<Rest...>> {};
}
 
template<concepts::TypeList L>
using PopFront = Type<detail::PopFrontHelper<L>>;
 
namespace detail {
    template<typename T>
    struct PopBackHelper : TypeConstant<List<>> {};
 
    template<typename T, typename U, typename... Rest>
    struct PopBackHelper<List<T, U, Rest...>> : TypeConstant<PushFront<Type<PopBackHelper<List<U, Rest...>>>, T>> {};
}
 
template<concepts::TypeList L>
using PopBack = Type<detail::PopBackHelper<L>>;
 
namespace detail {
    template<typename List, typename Acc, typename MetaFn>
    struct FoldHelper {};
 
    template<typename Acc, typename MetaFn>
    struct FoldHelper<List<>, Acc, MetaFn> : TypeConstant<Acc> {};
 
    template<typename T, typename... Rest, typename Acc, typename MetaFn>
    struct FoldHelper<List<T, Rest...>, Acc, MetaFn>
        : TypeConstant<Type<FoldHelper<List<Rest...>, Invoke<MetaFn, Acc, T>, MetaFn>>> {};
}
 
template<concepts::TypeList List, typename Init, concepts::MetaInvocable MetaFn>
using Fold = Type<detail::FoldHelper<List, Init, MetaFn>>;
 
namespace detail {
    template<typename List, typename Init, typename MetaFn>
    struct FoldRightHelper {};
 
    template<typename Init, typename MetaFn>
    struct FoldRightHelper<List<>, Init, MetaFn> : TypeConstant<Init> {};
 
    template<typename T, typename... Rest, typename Init, typename MetaFn>
    struct FoldRightHelper<List<T, Rest...>, Init, MetaFn>
        : TypeConstant<Invoke<MetaFn, Type<FoldRightHelper<List<Rest...>, Init, MetaFn>>, T>> {};
}
 
template<concepts::TypeList List, typename Init, concepts::MetaInvocable MetaFn>
using FoldRight = Type<detail::FoldRightHelper<List, Init, MetaFn>>;
 
namespace detail {
    template<typename Pred>
    struct FilterReducer {
        template<typename Acc, typename Val>
        using Invoke = Conditional<Invoke<Pred, Val>::value, PushBack<Acc, Val>, Acc>;
    };
}
 
template<concepts::TypeList List, concepts::MetaInvocable Pred>
using Filter = Fold<List, meta::List<>, detail::FilterReducer<Pred>>;
 
namespace detail {
    template<typename Needle, typename Replacement>
    struct ReplaceReducer {
        template<typename Acc, typename Val>
        using Invoke = PushBack<Acc, Conditional<concepts::SameAs<Val, Needle>, Replacement, Val>>;
    };
}
 
template<concepts::TypeList List, typename Needle, typename Replacement>
using Replace = Fold<List, meta::List<>, detail::ReplaceReducer<Needle, Replacement>>;
 
namespace detail {
    template<typename Pred, typename Replacement>
    struct ReplaceIfReducer {
        template<typename Acc, typename Val>
        using Invoke = PushBack<Acc, Conditional<Invoke<Pred, Val>::value, Replacement, Val>>;
    };
}
 
template<concepts::TypeList List, concepts::MetaInvocable Pred, typename Replacement>
using ReplaceIf = Fold<List, meta::List<>, detail::ReplaceIfReducer<Pred, Replacement>>;
 
namespace detail {
    template<typename...>
    struct TransformHelper {};
 
    template<typename... Types, typename Fun>
    requires(concepts::MetaInvocable<Fun> && (concepts::ValidInstantiation<Invoke, Fun, Types> && ...))
    struct TransformHelper<List<Types...>, Fun> : TypeConstant<List<Invoke<Fun, Types>...>> {};
}
 
template<concepts::TypeList List, typename Function>
using Transform = detail::TransformHelper<List, Function>::Type;
 
namespace detail {
    struct PushBackIfUnique {
        template<concepts::TypeList Lst, typename T>
        struct Impl : TypeConstant<PushBack<Lst, T>> {};
 
        template<concepts::TypeList Lst, typename T>
        requires(Contains<Lst, T>)
        struct Impl<Lst, T> : TypeConstant<Lst> {};
 
        template<concepts::TypeList Lst, typename T>
        using Invoke = Type<Impl<Lst, T>>;
    };
}
 
template<concepts::TypeList Lst>
using Unique = Fold<Lst, List<>, detail::PushBackIfUnique>;
 
namespace detail {
    template<typename T, typename U>
    struct ZipHelper : TypeConstant<List<>> {};
 
    template<typename T, typename U, typename... Ts, typename... Us>
    struct ZipHelper<List<T, Ts...>, List<U, Us...>>
        : TypeConstant<Concat<List<List<T, U>>, typename ZipHelper<List<Ts...>, List<Us...>>::Type>> {};
}
 
template<concepts::TypeList T, concepts::TypeList U>
requires(Size<T> == Size<U>)
using Zip = Type<detail::ZipHelper<T, U>>;
 
namespace detail {
    template<typename T, usize N>
    struct RepeatHelper;
 
    template<typename T>
    struct RepeatHelper<T, 0> : TypeConstant<List<>> {};
 
    template<typename T>
    struct RepeatHelper<T, 1> : TypeConstant<List<T>> {};
 
    template<typename T, usize N>
    requires(N > 1)
    struct RepeatHelper<T, N>
        : TypeConstant<Concat<Type<RepeatHelper<T, N / 2>>, Type<RepeatHelper<T, (N + 1) / 2>>>> {};
}
 
template<typename T, usize N>
using Repeat = Type<detail::RepeatHelper<T, N>>;
 
namespace detail {
    template<typename... Types>
    struct CartesianProductHelper {};
 
    template<>
    struct CartesianProductHelper<> : TypeConstant<List<List<>>> {};
 
    template<typename... Types>
    struct CartesianProductHelper<List<Types...>> : TypeConstant<List<List<Types>...>> {};
 
    template<typename... Ts, typename... Rest>
    struct CartesianProductHelper<List<Ts...>, Rest...>
        : TypeConstant<Concat<Transform<Type<CartesianProductHelper<Rest...>>, BindBack<Quote<PushFront>, Ts>>...>> {};
}
 
template<concepts::TypeList... Types>
using CartesianProduct = Type<detail::CartesianProductHelper<Types...>>;
 
// To produce an integer sequence using a minimal number of template
// instantiations, we partition the problem into halves, and construct
// the correcct sequence using the Concat helper.
namespace detail {
    template<typename T, typename X, typename Y>
    struct MakeIntegerSequenceConcatHelper;
 
    template<typename T, T... s1, T... s2>
    struct MakeIntegerSequenceConcatHelper<T, ListV<s1...>, ListV<s2...>> {
        using Type = ListV<s1..., (T(sizeof...(s1) + s2))...>;
    };
 
    template<typename T, usize count>
    struct MakeIntegerSequenceHelper {
        using A = meta::Type<MakeIntegerSequenceHelper<T, count / 2>>;
        using B = meta::Type<MakeIntegerSequenceHelper<T, count - count / 2>>;
        using Type = meta::Type<MakeIntegerSequenceConcatHelper<T, A, B>>;
    };
 
    template<typename T>
    struct MakeIntegerSequenceHelper<T, 1> : TypeConstant<ListV<T(0)>> {};
 
    template<typename T>
    struct MakeIntegerSequenceHelper<T, 0> : TypeConstant<ListV<>> {};
}
 
template<typename T, usize count>
using MakeIntegerSequence = Type<detail::MakeIntegerSequenceHelper<T, count>>;
 
template<usize count>
using MakeIndexSequence = MakeIntegerSequence<usize, count>;
 
template<typename... Types>
using IndexSequenceFor = MakeIndexSequence<sizeof...(Types)>;
}